ErgonomicsErgonomics Getting a Grip on

THE DEVELOPMENT OF musculoskeletal disorders (MSDs) in today’s workplace has become a substantial loss source in industry. This is evidenced in congressional hearings on the relationship between specific work/task actions and MSDs (Michael 1). As a result, the need to identify and quantify risk factors for the development of MSDs has become more important. It has also become more difficult due to the diversity of jobs and, more specifically, to different configurations of a given job. Force, repetition and posture have been identified as three risk factors associated with the incidence of MSDs (Silverstein, et al 779; Silverstein, et al 343; Putz-Anderson 21; OSHA). The National Research Council and Institute of Medicine identified forceful and repetitive hand motions as risk factors for the development of carpal tunnel syndrome (NRC-IM 1). It has also been reported that industrial workers who move their hands and wrists repeatedly and/or forcefully are susceptible to cumulative trauma disorders (CTDs) (Silverstein, et al 779; Silverstein, et al 343). Excessive grip force may be a risk factor for the development of MSDs in the hand, wrist, forearm and shoulder as well. In jobs that require repetitive gripping, an ergonomic evaluation should include a measure or estimation of the applied grip force. For example, many jobs within the meatpacking industry are hand-intensive and require considerable force (e.g., cutting tasks). OSHA has developed an ergonomic management guideline for that industry which suggests that tools and handles be selected to minimize excessive gripping in jobs where CTD risk factors include forceful exertions performed by an individual using the tools (OSHA 1). SH&E professionals can use various observational methods to quantify posture (Karhu, et al 199; Karhu, et al 13; Priel 570; Persson, et al 1). Similarly, repetition can be measured using a time-and-motion study (Armstrong, et al 325). However, direct measurement of applied forces and grip forces, with or without hand tools, can be difficult without sophisticated equipment. Consequently, practitioners often resort to Jeffrey S. Casey was the recipient of the 2001 ASSE Research Fellowship conducted at the Liberty Mutual Research Center for Safety and Health in Hopkinton, MA. He recently earned an M.S. in Occupational Ergonomics from the University of Massachusetts Lowell. Casey holds a B.S. in Human Kinetics from the University of Windsor (Ontario).